1. Technical Field
The present disclosure relates to holographic data storage. More particularly, the present disclosure relates to collinear holography.
2. Description of Related Art
Holographic data storage is a potential replacement technology in the area of high-capacity data storage. Holographic data storage research booms is occurred several times in the past. However, holographic data storage is still a potential replacement technology, not a commercial data storage solution.
Collinear holography is one possible holographic data storage solution. In collinear holography, the signal beam and the reference beam are collinear and are focused onto the disk by the same lens. Traditionally, the signal beam located on the center surrounded by the reference beam. Collinear holography has a simple structure, a possibility of backwards-compatibility, a shorter optical path difference between the signal beam and the reference beam, a lower requirement for the coherence length of the laser beam, a better shift selectivity, a larger wavelength tolerance, a larger medium tilt tolerance, high-capacity data storage, and high speed. Therefore, collinear holography has become the mainstream holographic data storage method.
However, the thermal deformation of the collinear holographic storage medium can change the transmission gratings, the reflection gratings, and the refractive index of the collinear holographic storage medium. As a result of the thermal deformation of the collinear holographic storage medium, the diffracted beam is weakened and has a poor point spread function (PSF).